System and method for treating ischemic stroke

ABSTRACT

A thromboembolic removal system for treating ischemic stroke includes an elongate member and a receiver on a distal portion of the elongate member. The receiver includes structural members arranged to form a sleeve having a central lumen. A plurality of the structural members form engaging elements having apex regions that extend into the central lumen. During use of the thromboembolic removal system, the receiver is advanced over a body of thromboembolic material within a blood vessel, causing the body to be received into the central lumen, and causing the engaging elements to engage the body within the lumen.

This application claims priority to U.S. Provisional Application No.60/609,028 filed Sep. 10, 2004, U.S. Provisional Application No.60/669,779, filed Apr. 8, 2005, and U.S. Provisional Application No.60/680,605, filed May 13, 2005, each of which is fully incorporatedherein by reference.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to the field of medicaltreatment and, more particularly, to a system and method for treatingischemic stroke which involves removing a thromboembolism from acerebral artery of a patient.

II. Discussion of the Prior Art

Stroke is a leading cause of death and disability and a growing problemto global healthcare. In the US alone, over 700,000 people per yearsuffer a major stroke and, of these, over 150,000 people die. Even moredisturbing, this already troubling situation is expected to worsen asthe “baby boomer” population reaches advanced age, particularly giventhe number of people suffering from poor diet, obesity and/or othercontributing factors leading to stroke. Of those who survive a stroke,approximately 90% will have long-term impairment of movement, sensation,memory or reasoning, ranging from mild to severe. The total cost to theUS healthcare system is estimated to be over $50 billion per year.

Strokes may be caused by a rupture of a cerebral artery (“hemorrhagicstroke”) or a blockage in a cerebral artery due to a thromboembolism(“ischemic stroke”). A thromboembolism is a detached blood clot thattravels through the bloodstream and lodges so as to obstruct or occludea blood vessel. Between the two types of strokes, ischemic strokecomprises the larger problem, with over 600,000 people in the USsuffering from ischemic stroke per year.

Ischemic stroke treatment may be accomplished via pharmacologicalelimination of the thromboembolism and/or mechanical elimination of thethromboembolism. Pharmacological elimination may be accomplished via theadministration of thombolytics (e.g., streptokinase, urokinase, tissueplasminogen activator (TPA)) and/or anticoagulant drugs (e.g., heparin,warfarin) designed to dissolve and prevent further growth of thethromboembolism. Pharmacologic treatment is non-invasive and generallyeffective in dissolving the thromboembolism. Notwithstanding thesegenerally favorable aspects, significant drawbacks exist with the use ofpharmacologic treatment. One such drawback is the relatively long amountof time required for the thrombolytics and/or anticoagulants to takeeffect and restore blood flow. Given the time-critical nature oftreating ischemic stroke, any added time is potentially devastating.Another significant drawback is the heightened potential of bleeding orhemorrhaging elsewhere in the body due to the thombolytics and/oranticoagulants.

Mechanical elimination of thromboembolic material for the treatment ofis chemic stroke has been attempted using a variety of catheter-basedtransluminal interventional techniques. One such interventionaltechnique involves deploying a coil into a thromboembolism (e.g. viacorkscrew action) in an effort to ensnare or envelope thethromboembolism so it can be removed from the patient. Although animprovement over pharmacologic treatments for ischemic stroke, suchcoil-based retrieval systems have only enjoyed modest success(approximately 55%) in overcoming ischemic stroke due to thromboembolicmaterial slipping past or becoming dislodged by the coil. In the lattercase, the dislodgement of thromboembolic material may lead to anadditional stroke in the same artery or a connecting artery.

Another interventional technique involves deploying a basket or netstructure distally (or downstream) from the thromboembolism in an effortto ensnare or envelope the thromboembolism so it can be removed from thepatient. Again, although overcoming the drawbacks of pharmacologictreatment, this nonetheless suffers a significant drawback in that theact of manipulating the basket or net structure distally from theoccluded segment without angiographic roadmap visualization of thevasculature increases the danger of damaging the vessel. In addition,removing the basket or net structure may permit if not causethromboembolic material to enter into connecting arteries. As notedabove, this may lead to an additional stroke in the connecting artery.

A still further interventional technique for treating ischemic strokeinvolves advancing a suction catheter to the thromboembolism with thegoal of removing it via aspiration (i.e. negative pressure). Althoughgenerally safe, removal via aspiration is only effective with relativelysoft thrombus-emboli. To augment the effectiveness of aspirationtechniques, a rotating blade has been employed to sever or fragment thethromboembolism, which may thereafter be removed via the suctioncatheter. While this rotating blade feature improves the effectivenessof such an aspiration technique, it nonetheless increases the danger ofdamaging the vessel due to the rotating blade.

The foregoing interventional techniques, as well as others in the priorart, all suffer one or more drawbacks and are believed to be sub-optimalfor treating ischemic stroke. The present invention is directed atovercoming, or at least improving upon, the disadvantages of the priorart.

BRIEF DESCRIPTION OF THE DRAWINGS

Many advantages of the present invention will be apparent to thoseskilled in the art with a reading of this specification in conjunctionwith the attached drawings, wherein like reference numerals are appliedto like elements and wherein:

FIG. 1 is a partial sectional side view of one embodiment of athromboembolic removal system, including a guide and occlusion catheter,a delivery and aspiration catheter, an aspiration pump, a thromboembolicreceiver, and a thromboembolic separator;

FIG. 2 is a partial sectional side view of a delivery and aspirationcatheter forming part of the thromboembolic removal system shown in FIG.1, illustrating a thromboembolic receiver element in an undeployedstate;

FIG. 3 is a partial sectional side view of a delivery and aspirationcatheter forming part of the thromboembolic removal system shown in FIG.1, illustrating the thromboembolic receiver element in a deployed state;

FIG. 4A is a perspective view depicting an alternate embodiment of athromboembolic receiver, equipped with a plurality of engagementelements;

FIG. 4B is a cross-section view taken along the plane designated 4B-4Bin FIG. 4A;

FIG. 4C is a perspective view illustrating the distal portion of thethromboembolic receiver of FIG. 4A;

FIG. 5 is a plan view of the alternate thromboembolic receiver of FIG.4. Although the receiver is preferably a tubular structure, FIG. 5 showsit opened and flattened into a sheet so that its features may be moreeasily viewed;

FIG. 6 is a top view illustrating one embodiment of a flex region foruse in flexibly coupling the thromboembolic receiver, such as thereceiver of FIG. 4A, to an elongate member or a delivery and aspirationcatheter;

FIG. 7 is a perspective view of an alternate thromboembolic receiver,equipped with a plurality of engagement elements capable of beingselectively deployed after the deployment of the thromboembolicreceiver;

FIG. 8A is perspective view of a thromboembolic receiver having featuresfor facilitating reloading of the receiver into a catheter;

FIG. 8B is a plan view similar to the view of FIG. 5 showing thethromboembolic receiver of FIG. 8A;

FIG. 8C is a perspective view of a proximal portion of thethromboembolic receiver of FIG. 8A and the distal portion of theelongate member coupled to the thromboembolic receiver, illustratingretraction of the thromboembolic receiver into a delivery and aspirationcatheter;

FIGS. 9 and 10 are partial sectional side views of one embodiment of athromboembolic disrupter or separator in use with a delivery andaspiration catheter;

FIG. 11A is an enlarged view of the separator element forming part ofthe thromboembolic separator shown in FIGS. 9 and 10;

FIG. 11B is a side elevation view of an alternate embodiment of athromboembolic separator;

FIG. 11C is an enlarged view of the separator element forming part ofthe thromboembolic separator shown in FIG. 11B;

FIG. 11D is a side elevation view similar to FIG. 11C showing anotheralternate embodiment of a thromboembolic separator;

FIG. 12 is a partial sectional view of a patient illustrating thethromboembolic removal system of FIG. 1 in use within the arterialsystem;

FIG. 13 is a partial sectional view of a patient illustrating the distalregion of the thromboembolic removal system of FIG. 1 in use within acerebral artery;

FIG. 14 is a partial section side view illustrating advancement of aguide wire to a thromboembolism;

FIG. 15 is a partial section side view illustrating advancement of theguide and occlusion catheter, with the balloon in a deflated state;

FIG. 16 is a partial section side view illustrating inflation of theballoon occlusion member to arrest the blood flow within the arterycontaining the thromboembolism;

FIG. 17 is a partial section side view illustrating the step ofadvancing the delivery and aspiration catheter of FIGS. 1-3 to a pointproximal to the thromboembolism according to a method for using thesystem of FIG. 1;

FIG. 18 is a partial section side view illustrating deployment of thethromboembolic receiver of FIGS. 1-3;

FIG. 19 is a partial section side view illustrating advancement of thedelivery and aspiration catheter of FIGS. 1-3 distally such that thethromboembolic receiver of FIGS. 1-3 engages (fully or partially) thethromboembolism;

FIGS. 20 and 21 are partial section side views illustrating movement ofthe thromboembolic receiver of FIGS. 1-3 into the guide and occlusioncatheter so as to remove the thromboembolism;

FIG. 22 is a partial section side view illustrating use of thethromboembolic separator of FIGS. 1 and 9-11C to engage the distal endof the thromboembolism;

FIG. 23 is a partial section side view illustrating use of thethromboembolic separator of FIGS. 1 and 9-11C to fragmentize and/orsoften the thromboembolism and/or aid aspiration;

FIG. 24 is a partial section view illustrating independent use of thethromboembolic separator of FIGS. 1 and 9-11C to fragmentize and/orsoften the thromboembolism and/or aid aspiration;

FIGS. 25 and 26 are partial section side views illustrating advancementof the thromboembolic receiver of FIGS. 4-6 distally such that itenvelopes the thromboembolism; and

FIGS. 27 and 28 are a partial section side views illustrating withdrawalof the thromboembolic receiver of FIGS. 4-6 and the delivery andaspiration catheter into the guide and occlusion catheter so as toremove the thromboembolism.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The thromboembolic removal system disclosed hereinboasts a variety of inventive features and components that warrantpatent protection, both individually and in combination.

System Features

FIG. 1 illustrates an exemplary embodiment of a thromboembolic removalsystem 10. The thromboembolic removal system 10 includes a guide andocclusion catheter 12, a delivery and aspiration catheter 14, athromboembolic disrupter or separator 16, and an aspiration pump 18. Aswill be described in greater detail below, the thromboembolic removalsystem 10 advantageously provides the ability to remove athromboembolism from a cerebral artery within a patient while overcomingthe drawbacks and limitations of the prior art.

The guide and occlusion catheter 12 includes a tubular catheter member20 having a main lumen 22 extending between a proximal end 24 and adistal end 26. The catheter member 20 may be constructed from any numberof compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the entry point into the vasculature, thelocation of the thromboembolism, variances in patient anatomy, and anyextenuating circumstances. In an exemplary embodiment, the cathetermember 20 may be constructed from nylon with embedded stainless steelbraid and dimensioned having a length ranging from 70 cm to 110 cm and adiameter ranging from 5 French (0.065 inch) to 9 French (0.117 inch). Aballoon occlusion member 28 is disposed at or near the distal end 26. Toselectively inflate the occlusion member 28, an inflation port 30 isprovided in fluid communication with the occlusion member 28 via atleast one lumen (not shown) disposed within the wall of the tubularcatheter member 20. A seal 32 is provided for passing the delivery andaspiration catheter 14 through the main lumen 22 of the guide andocclusion catheter 12 in leak-free, hemostatic fashion.

The delivery and aspiration catheter 14 includes a tubular catheterelement 34 having a main lumen 36 extending between a distal end 38 anda proximal end 40. The catheter member 34 may be constructed from anynumber of compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the entry point into the vasculature, thelocation of the thromboembolism, variances in patient anatomy, and anyextenuating circumstances. In an exemplary embodiment, the cathetermember 34 may be constructed from pebax with embedded stainless steelbraid and dimensioned having a length ranging from 130 cm to 170 cm anda diameter ranging from 2.5 French (0.032 inch) to 5 French (0.065inch).

The delivery and aspiration catheter 14 also includes a hub assembly 42coupled to the proximal end 40 for the purpose of coupling the lumen 36to the aspiration pump 18. The hub assembly 42 also includes a seal 44for allowing the passage of the thromboembolic separator 16 (as well asany pushing devices to deploy a receiver element 46, as will bediscussed below) through the lumen 36 in leak-free, hemostatic fashion.The lumen is preferably coated with PTFE or another of the varioussuitable lubricious materials known in the art.

As best viewed with reference to FIGS. 2-3, the thromboembolic receiverelement 46 is capable of being retained in a withdrawn or undeployedstate within the lumen 36 (FIG. 2) and selectively pushed out and/orunsheathed from the distal end 38 into a deployed state (FIG. 3). Thethromboembolic receiver 46 may be constructed from any number ofcompositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the location of the thromboembolism,variances in patient anatomy, and the size and shape of thethromboembolism. As best viewed in FIGS. 3 and 5, the thromboembolicreceiver 46 is formed from a plurality of strut members 47, which uponbeing deployed, create a multitude of generally diamond-shaped openings49 along the periphery of the thromboembolic receiver 46. According toone embodiment, as shown in FIGS. 18-23, the resulting points at thedistal region of the thromboembolic receiver 46 are equipped with blunttip features 51 to facilitate passage of the thromboembolic receiver 46through the cerebral artery without snagging or becoming otherwise stuckon the arterial walls or branch vessels leading into the cerebralartery.

A pusher element 48 may be provided within the catheter element 34 foruse in advancing or pushing the receiver element 46 from within thelumen 36 to assume a fully or partially deployed state. By way ofexample only, the pusher element 48 comprises an elongate member 50 ofsuitable construction (e.g. wire or wire-wound) having a distal abutment52 dimensioned to contact proximal terminal(s) 54 forming part of (orcoupled to) the receiver element 46. Although not shown, it will beappreciated that the pusher element 48 may comprise any number ofsuitable devices for pushing the receiver element 46 for deployment,including but not limited to a catheter having a distal end dimensionedto contact the proximal terminal(s) 54 of the receiver element 46. Inone embodiment, such a pusher-catheter may have an internally disposedlumen dimensioned to receive and/or pass the thromboembolic separator16.

FIG. 4A illustrates a thromboembolic receiver 146 of an alternateembodiment. The thromboembolic receiver 146 may be constructed from anynumber of compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the location of the thromboembolism,variances in patient anatomy, and the size and shape of thethromboembolism. In a preferred embodiment, the thromboembolic receiver146 is constructed from Nitinol with “shape memory” or superelasticcharacteristics. In this fashion, the thromboembolic receiver 146 iscapable of being retained in a constrained form or shape prior todeployment. The receiver may be formed by laser cutting features into alength of Nitinol tubing, and then chemically etching and shape-settingthe material one or more times using methods known to those skilled inthe art.

Referring to FIG. 4A, receiver 146 is mounted to an elongate member 151preferably proportioned to extend through lumen 36 (FIG. 1) of thedelivery and aspiration catheter 14. Strut members or “legs” 162 extendbetween receiver 146 and elongate member 151 and are preferably attachedto the elongate member 151 using bonding, shrink tubing, or other knownmethods. In a preferred embodiment, member 151 is an elongate rod,catheter, wire or other elongate member. In this embodiment, thethromboembolic receiver 146 is proportioned so that it may beconstrained in a compressed position within the delivery and aspirationcatheter 14 (in a manner similar to that shown in FIGS. 1-3).Alternatively, the elongate member 151 may be the delivery andaspiration catheter 14, in which case the receiver 146 and delivery andaspiration catheter 14 are proportioned to extend through the guide andocclusion catheter 12.

In either event, the thromboembolic receiver 146 may be automaticallydeployed—due to the shape memory or superelastic characteristics ofNitinol—by simply advancing the thromboembolic receiver 146 out of theelement constraining it in the undeployed state (e.g. the guide andocclusion catheter 12 or the delivery and aspiration catheter 14). Oncedeployed, the thromboembolic receiver 146 may be employed to retrieve athromboembolism. The dimensions of the receiver 146 are preferablyselected such that when it is in an expanded condition at bodytemperature, the exterior surface of the distal portion of the receivercontacts the surrounding walls of the blood vessel. In one embodimentsuitable for most intracranial vessels, the receiver may expand to amaximum outer diameter of approximately 2-6 mm, and more preferably 2-5mm. For other applications such as procedures within the common carotidartery, a maximum outer diameter in the range of approximately 6-9 mmmay be suitable.

The thromboembolic receiver 146 may be formed having any of a variety ofsuitable geometries and features without departing from the scope of thepresent invention. According to one embodiment shown in FIGS. 4A and 5,the thromboembolic receiver 146 is formed from a plurality of strutmembers, which upon being deployed, create a multitude of generallyrectangular openings 149 (best viewed in FIG. 5) along the periphery ofthe thromboembolic receiver 146. This is accomplished, by way ofexample, by providing a plurality of longitudinal strut members or“standards” 150 (which are generally parallel to the longitudinal axisof the delivery and aspiration catheter 14), and a plurality oftransverse strut members 152 (which extend generally perpendicularlybetween the adjacent standards). In a preferred embodiment, the strutmembers collectively define a generally cylindrical distal portionhaving a central lumen 147 as shown in FIG. 4B.

The transverse strut members 152 may include any number of curves orundulations, such as curves 153 a shown near the points of intersectionbetween the transverse strut members 152 and the standards 150, as wellas the curves 153 b midway between the points of intersection as shownin FIG. 5. Such curves or undulations help allow the thromboembolicreceiver 146 to fold into a compressed or constrained state, which isrequired in order to dispose the thromboembolic receiver 146 within thedelivery and aspiration catheter 14 or within the guide and occlusioncatheter 12.

The transverse strut members 152 form, in a preferred embodiment, aproximal cuff 154 located closest to the delivery and aspirationcatheter 14, a distal cuff 156 located at the distal or open end of thethromboembolic receiver 146, and a middle cuff 158 located at some pointbetween the proximal and distal cuffs. Each cuff (proximal 154, middle158, and distal 156) is a circumferential ring designed to enhance thestructural support and stability of the thromboembolic receiver 146, aswell as to aid in maintaining the thromboembolic receiver 146 in adesired shape upon deployment (for improved apposition to the vesselwall to optimize thromboembolic retrieval).

The structural support provided by the cuffs 154-158 may be augmented byproviding one or more stabilizing strut members 160 within one or moreof the generally rectangular openings 149. According to one embodiment,these stabilizing strut members 160 may take the form of a “V” extendingfrom either the proximal end or distal end of a given generallyrectangular opening 149 within the thromboembolic receiver 146. In apreferred embodiment, such “V” shaped stabilizing strut members 160 areprovided within the proximal and distal set of generally rectangularopenings 149 within the thromboembolic receiver 146. This advantageouslyadds to the structural stability of the proximal and distal regions ofthe thromboembolic receiver 146. Regardless of their specific shape, thestabilizing strut members 160 preferably include folding regions orapexes 169 that allow them to fold at the apexes 169 (see arrows A inFIG. 5) when the receiver is compressed into the collapsed position.Additionally, the receiver is preferably constructed so as to permit thestrut members 160 to fold in the region where they intersect with otherelements forming the receiver (e.g. in the FIG. 5 embodiment, the regionof intersection between strut members 160 and standards 150).

While structural stability of the thromboembolic receiver 146 is adesired goal, it is also desired to have certain aspects of flexibility.According to one embodiment, relative flexibility is provided at thejunction between the thromboembolic receiver 146 and the elongate member151 (or the distal end of the delivery and aspiration catheter 14). Thisis accomplished, by way of example only, by providing the plurality ofconnector strut members or “legs” 162 extending between the proximalcuff and the elongate member 151 to include (as best viewed in FIG. 5) aflex region 164 near the distal end of the elongate member 151. The flexregions 164 may be formed into any shape that will add flexibility tothe strut members 162 without comprising the user's ability to transmitaxial forces along the length of the strut members 162. In an alternateembodiment shown in FIG. 6, the flex regions 164 a may comprise aplurality of meandering “S” shaped struts 166 a at the proximal ends ofthe connector struts 162. According to another embodiment, a flex regionor spring region 168 (FIG. 5) (which may comprise one or more “S” shapedcurves or other shapes designed to provide flexibility while maintainingadequate column strength) may be provided at the junction betweenadjacent longitudinal strut members or standards 150. In both instances,such flex regions 164, 168 are advantageous in that they allow thethromboembolic receiver 146 to better track and follow tortuous vesselswithout sacrificing needed column strength.

According to a further embodiment, the thromboembolic receiver 146 mayalso include a variety of features to augment engagement between thethromboembolic receiver 146 and the thromboembolism. This may beaccomplished, by way of example only, by providing a plurality ofengagement elements 170 on the thromboembolic receiver. As best viewedin FIGS. 4A, 4B and 5, the engagement elements 170 may, according to oneembodiment, take the form of a “V” shaped structure coupled at or nearthe distal end of the thromboembolic receiver 146 and extending betweenadjacent standards 150. The engagement elements preferably angle intothe lumen 147 of the thromboembolic receiver (see FIGS. 4B and 4C) so asto permit engagement of a thromboembolism captured within the lumen. Anynumber of engagement elements 170 may be employed without departing fromthe scope of the present invention. In one embodiment, three (3)separate engagement elements 170 may be employed, each being disposedone hundred and twenty (120) degrees from one another along theperiphery of the thromboembolic receiver 146. In a preferred embodiment,the engagement elements 170 take the form of a plurality of thestabilizing strut members 160 as shown in FIGS. 4A and 5.

The engagement elements 170 may be deployed automatically when thethromboembolic receiver 146 is deployed (as shown in FIG. 4-5). Inaccordance with another aspect of the invention shown in FIG. 7, theengagement elements 170 a may also be selectively deployed at any pointfollowing the deployment of the thromboembolic receiver 146 a. Accordingto the FIG. 7 embodiment, the selective deployment of the engagementelements 170 a is accomplished by passing one or more elongate elements172 through the thromboembolic receiver 146 a such that the engagementelements 170 a are prevented from extending medially into the lumen ofthe thromboembolic receiver 146. When deployment is desired, a user needonly pull the elongate elements 172 in a proximal direction (towards theuser) until the engagement elements 170 a are set free from theconstraint of the elongate elements 172. When this occurs, the “shapememory” or superelastic nature of the engagement elements 170 a willcause them to assume their natural state, extending medially into thelumen of the thromboembolic receiver 146 a. In this fashion, theengagement elements 170 a will engage the thromboembolism and thus aidor enhance the ability of the thromboembolic receiver 146 a to remove athromboembolism.

The thromboembolic receiver may be provided with features that allow asurgeon to retract the receiver back into the delivery and aspirationcatheter after the receiver has been partially or fully deployed into ablood vessel. This might be necessary if, perhaps, the surgeon receivesangiographic or tactile feedback indicating that a separator would be apreferred tool for removal of a particular embolism, or that a receiverof a different size would be more suitable for a particular procedure.

FIG. 8A illustrates one example of an embodiment of a thromboembolicreceiver 146 b that is similar to the receiver 146 of FIG. 4, but thatincludes features that facilitate reloading of the receiver into thedelivery and aspiration catheter 14. As shown, receiver 146 b of theFIG. 8A embodiment includes a single, distal, cuff 152 b and a pluralityof longitudinal strut members 150 b extending proximally from the cuff152 b.

Structural support members 160 b are arranged in a distal row 171 aadjacent to the cuff 152 b, and a more proximal row 171 b as shown inFIG. 8B. As with the FIG. 4 embodiment, a plurality of the structuralsupport members 160 b in the distal row are inwardly biased into thecentral lumen 147 b of the receiver 146 b so as to function asengagement members 170 b for engaging a thromboembolism.

Three types of stabilizing strut members extend towards the proximal endof the receiver 146 b. First, strut members 162 b extend distally fromthe apexes of those of the structural support members 160 b in thedistal row 171 a that do not function as engagement members. These strutmembers 162 b are coupled at an intermediate point to the apexes oflongitudinally aligned support members 160 b in the proximal row 171 b.Second, strut members 162 c form the proximal extensions of thelongitudinal strut members 150 b and include eyelets 163 at theirproximal ends. Third, strut members 162 d extend from the apexes ofthose of the structure support members 160 b in the proximal row thatare longitudinally aligned with the engagement members 170 b.Flexibility may be added to the receiver 146 b may constructing some orall of the strut members to include flex regions of the type describedin connection with earlier embodiments (see, e.g. flex regions 168 ofFIG. 5).

Referring to FIG. 8C, the receiver 146 b includes a pusher or elongatemember 151 b that includes a lumen 165 at its distal end. Duringassembly of the receiver 146 b, the proximal ends of strut members 162 band 162 d are positioned within the lumen 165 as shown and are allowedto slide freely within the lumen 165. The proximal ends of strut members162 c are bonded to the exterior surface of the elongate member 151 busing heat shrink tubing 167 or other suitable material. The eyelets 163facilitate bonding by allowing the bonding material to flow into theopenings of the eyelets, thereby exposing a larger portion of each strutmember 162 c to the bonding material. If desired, the strut members 162b and 162 d may be somewhat longer than the strut members 162 c at theproximal end of the receiver, to allow them to be easily identified forinsertion into the lumen 165 during assembly.

If it should be necessary to withdraw the receiver 146 b back into thedelivery and aspiration catheter 14 from a fully or partially deployedstate, the elongate member 151 b is withdrawn in a proximal directionrelative to the catheter as shown in FIG. 8C. As the receiver 146 bmoves into the catheter 14, the receiver begins to fold at the apexes ofthe structural support members 160 b, thereby pushing the strut members162 b and 162 d in a proximal direction. Folding is more easilyaccomplished than with the receiver 146 of FIG. 4 due to the fact thatcertain of the structural support members 160 b are interconnected attheir apexes by strut members 162 b. Thus, the folding of one member 160b in the proximal row 171 b will facilitate the folding of acorresponding member 160 b in the distal row 171 a. The strut members162 b and 162 d are allowed to slide freely within the lumen 165 of theelongate member 151 b so that they will not resist folding of themembers 160 b during withdrawal of the receiver 146 b into the catheter14.

A first embodiment of a thromboembolic separator is shown in FIG. 9. Thethromboembolic separator 16 of the first embodiment includes anelongated element 56 having a proximal end 58 and a distal end 60. Theelongated element 56 may be constructed from any number of compositionshaving suitable biocompatibility and strength characteristics, and maybe dimensioned in any number of suitable sizes and lengths dependingupon the entry point into the vasculature, the location of thethromboembolism, variances in patient anatomy, and any extenuatingcircumstances. In an exemplary embodiment, the elongated element 56 maybe constructed from stainless steel and/or Nitinol and dimensionedhaving a length ranging from 150 cm to 200 cm and a diameter rangingfrom 0.010 inch to 0.021 inch. A lubricious surface (e.g. a PTFEcoating, hydrophilic coating, or other suitable coatings) may be appliedto all or a portion of the elongate element 56 to facilitate movement ofthe element within the lumen of the delivery/aspiration catheter 14and/or within the vasculature.

If desired, the elongate element 56 may take the form of a guide wire ofthe type used in various vascular applications. The elongate element maythus optionally include a coiled distal section 57 (FIG. 11B) havingsufficient flexibility to prevent trauma to vascular tissues duringadvancement of the guidewire. In an exemplary embodiment, coiled distalsection 57 may have a length in the range of approximately 27-33 cm. Thecoil is preferably positioned around an inner mandrel or core (notshown) of a type commonly found in coiled guidewires.

The “working end” of the separator 16 includes a generally blunt tipelement 62 attached or forming part of the distal end 60 of theelongated element 56, and a separator element 64 attached or formingpart of the elongated element 56. The tip element 62 is preferablydimensioned to pass through or against a thromboembolism so as to softenor fragment the thromboembolism for removal. The blunt nature of the tipelement 62 is advantageously atraumatic such that it will not causedamage to the interior of the vasculature during use. The separator 16also assists in removing any clogs or flow restrictions that may developwithin the lumen 36 due to the passage of thromboembolic materialtherethrough during aspiration.

In one embodiment, as best shown in FIG. 11A, the separator element 64may take the form of a basket that is generally conical in shape, withan opening 66 facing proximally along the elongated element 56. Theseparator basket 64 is dimensioned to assist in the thromboembolicfragmentation process, as well as to receive such thromboembolicfragments to aid in their removal. In one embodiment, the separatorbasket 64 is provided having a web 68 and one or more support members70. The support members 70 are dimensioned to bias the web 68 into thegenerally open position shown and, if desired, to allow the web 68 toassume a generally closed position (not shown, but generally flushagainst the elongated element 56) as the separator 16 is passed throughdelivery and aspiration catheter 14, a catheter-style pusher asdescribed above, and/or the thromboembolism itself.

An alternative embodiment of a separator 16 a is shown in FIGS. 11B and11C, in which like reference numerals are used to identify featuressimilar to those shown in FIGS. 9, 10 and 11A. Separator 16 a differsfrom separator 16 of FIGS. 9, 10 and 11A primarily in the features ofseparator element 64 a. Referring to FIG. 11B, separator element 64 a isa conical member formed of a polymeric material such as polyurethane orPebax® polyether block amides, to name a few. The separator element 64 ais preferably a solid member, with a surface 65 facing in the proximaldirection, and with the taper of the element oriented in a distaldirection. Surface 65 may be contoured in a variety of ways. Forexample, surface 65 may be slightly concave as shown in FIG. 11B,substantially planar as shown in FIG. 11C, or slightly convex as shownin FIG. 11D.

The separator element 64 a is positioned on the coiled distal section 57of the elongate element 56. The pitch of a portion of the coiled section57 may be decreased in certain regions of the coiled distal section 57.Opening the spacing in the coil in this manner can facilitate adhesionbetween the polymeric material of the separator element and the coilmaterial during the molding process. The spacing between the separatorelement 64 a and the distal end 60 of the elongate element 56 ispreferably long enough to allow the distal-most portion of the elongateelement sufficient flexibility to move atraumatically through thevasculature, but short enough to prevent folding of the distal-mostportion during advancement of the elongate element 56. In an exemplaryembodiment, the distal end of separator element 64 a may be positionedapproximately 3-9 mm from the distal end 60. It should be noted that themandrel or core (not shown) within the coiled section 57 of the elongateelement 56 might have a tapered diameter selected to enhance theflexibility of the coiled section.

A handle member 72 (FIG. 9) is provided at the proximal end 58 of theseparator to provide a purchase point for a user to advance and/ormanipulate the atraumatic tip element 62 and separator 64/64 a. In oneembodiment, the handle member 72 may be coupled to the elongated element56 in any suitable fashion, including but not limited to providing agenerally rigid extension (not shown) disposed within the elongatedelement 56 for the purpose of coupling the two components together. Thiscoupling may be augmented or strengthened through the use of any numberof adhesives or fusing techniques.

The separator 16 may be provided in a variety of different permutationswithout departing from the scope of the present invention. For example,in addition to the “self deployable” embodiment described above, theseparator basket 64 of FIG. 11A may be selectively deployed, such as byequipping the separator basket 64 with a mechanism to selectively biasor open the support members 70 from an initial position lying generallyflush against the elongated element 56 to a generally radially expandedposition (shown with arrows in FIG. 11A).

It will be appreciated that the guide and occlusion catheter 12, thedelivery and aspiration catheter 14, the thromboembolic separator 16and/or the thromboembolic receiver 46 may be provided with any number offeatures to facilitate the visualization of these elements duringintroduction and usage, including but not limited to having the distalregions equipped with radiopaque markers for improved radiographicimaging.

As discussed previously in connection with FIG. 1, the variouscomponents described herein may be provided as part of a system 10 forremoving thromboembolic material. The thromboembolic removal system 10may include a guide and occlusion catheter 12, a delivery and aspirationcatheter 14, a thromboembolic separator 16/16 a, a thromboembolicreceiver (e.g. receiver 46 or 146), and an aspiration pump 18, as wellas guidewires and/or other tools appropriate for the procedure. In oneembodiment, multiple receivers 46/146 may be provided, allowing thesurgeon to sequentially retrieve several thromboembolisms during thecourse of a procedure. For simplicity, each separate receiver may beprovided with a separate delivery and aspiration catheter. The system 10may additionally be provided with instructions for use setting forth anyof the various methods of use described herein, or equivalents thereof.

System Use

Methods of using the thromboembolic removal system 10 will now bedescribed with reference to FIGS. 12-28. As shown generally in FIGS.12-13, in a first exemplary method the thromboembolic removal system 10is introduced into the patient's vasculature, such as via the Seldingertechnique. FIG. 14 illustrates the first step of this process, whichinvolves advancing a guide wire 104 to a point proximal to athromboembolism 100. The guide wire 104 may comprise any number ofcommercially available guide wires, the operation of which is well knownin the art. However, in one method, the elongate member 56 (FIG. 11B) ofthe separator 16 functions as the guidewire 104.

FIG. 15 illustrates a second step, which involves advancing the guideand occlusion catheter 12 over the guide wire 104 to a point proximal tothe thromboembolism. The next step, shown in FIG. 16, preferablyinvolves inflating the balloon occlusion member 28 so as to arrest theblood flow within the cerebral artery 102 containing the thromboembolism100. As shown in FIG. 17, the delivery and aspiration catheter 14 isthen advanced through the guide and occlusion catheter 12 such that thedistal end 38 of the delivery and aspiration catheter 14 is positionedat a point proximal to the thromboembolism 100. This may be facilitatedby advancing the delivery and aspiration catheter 14 over the guide wire104 and/or an exchange-length guide wire (not shown but well known inthe art) extending through the guide and occlusion catheter 12.

At this point, as shown in FIG. 18, the thromboembolic receiver 46 isdeployed from the distal end 38 of the delivery and aspiration catheter14. In one embodiment, the balloon occlusion 28 may be inflated at thispoint (as opposed to inflating it before the delivery and aspirationcatheter 14 is advanced, as shown in FIG. 16). The delivery andaspiration catheter 14 is then advanced distally—as shown in FIG.19—such that the thromboembolic receiver 46 engages and/or envelops(partially or fully) the thromboembolism 100. At this point, as shown inFIGS. 20 and 21, the delivery and aspiration catheter 14 may bewithdrawn into the guide and occlusion catheter 12 to remove thethromboembolism 12 from the patient 16.

To augment the ability to remove the thromboembolism 100, or in theinstance the thromboembolic receiver 46 does not initially engage thethromboembolism 100, the aspiration pump 18 may be activated toestablish negative pressure within the delivery and aspiration catheter14. In this fashion, negative pressure will be created within thecerebral artery 102 and exerted upon the thromboembolism 100. As notedabove, the separator 16 (or the separator 16 a of FIGS. 11B-D) may beemployed during this process (e.g. advancing and retracting it withinthe lumen 36 of the delivery and aspiration catheter 14) to remove anyclogs or flow restrictions due to the passage of thromboembolic materialthrough the lumen 36. The negative pressure will serve to draw thethromboembolism 100 into (partially or fully) the thromboembolicreceiver 46. The delivery and aspiration catheter 14 may then bewithdrawn into the guide and occlusion catheter 12 to remove thethromboembolism 100 from the patient.

To further augment the ability to remove the thromboembolism 100, or inthe instance the aspiration pump 18 does not adequately draw all or mostof the thromboembolism 100 into the receiver 46, the thromboembolicseparator 16/16 a may be advanced into contact with a portion of thethromboembolism, or completely through the thromboembolism 100 as shownin FIG. 22, and employed to bias or engage the distal end of thethromboembolism 100. This will increase the surface area of engagementwith the thromboembolism 100, which will advantageously allow it to bewithdrawn into the guide and occlusion catheter 12 such as bywithdrawing the separator 16/16 a and delivery and aspiration catheter14 simultaneously into the guide and occlusion catheter 12.

As shown in FIG. 23, the separator 16/16 a may also be selectivelyadvanced and retracted through the thromboembolism 100 (or thatremaining outside the receiver 46). This will serve to break up orotherwise soften the thromboembolism 100. Advancing and retracting theseparator 16/16 a also serves to remove any clogs or flow restrictionswithin the lumen of the delivery and aspiration catheter 14 duringaspiration due to the passage of thromboembolic material through thelumen 36 of the delivery and aspiration catheter 14. In either event,the aspiration pump 18 will draw or bias the thromboembolic fragments106 or the softened thromboembolism 100 into the thromboembolic receiver46 and/or into catheter 14. The delivery and aspiration catheter 14 maythen be withdrawn such that the thromboembolic receiver 46 is drawn intothe guide and occlusion catheter 12 to remove the thromboembolism 100from the patient.

Selective advancement of the separator element 64 through thethromboembolism and retraction of the separator element into thedelivery and aspiration catheter 14, preferably in combination withaspiration, can additionally be used to carry small “bites” of thethromboembolic material into the catheter 14. For example, the separatorelement 64 may be passed through the thromboembolic material, displacingsome material and thus forming a channel in the material as it movesdistally. Once the separator element is positioned further into, ordistally of, the thromboembolism, some of the displaced material mayflow back into this channel. Subsequent retraction of the separatorelement 64 through the material (e.g. through the re-filled channel)will then draw some of the material into the catheter 14. To facilitatethis procedure, the separator element 64 and the catheter 14 arepreferably provided with fairly tight tolerances between the diameter ofthe catheter lumen 36 and the greatest diameter of the separator element64. For example, in one exemplary embodiment, the outer diameter ofseparator element 64 and the diameter of lumen 36 may differ byapproximately 0.003-0.008 inches.

An alternative method will next be described in which the receiver anddisrupter are preferably used independently of one another, althoughcombined use such as that described in connection with the firstexemplary method might also be used. This method will be described asperformed using the thromboembolic receiver 146 and the separator 16 a,however it should be appreciated that other embodiments of thesecomponents may alternatively be used in the disclosed method.

According to the alternative method, an initial determination is madeconcerning whether use of receiver 146 or separator 16 a will first beemployed. This determination may be made at random, although in apreferred method the surgeon selects the appropriate tool based on adetermination of the likely nature of the thromboembolic material thatis to be removed. In particular, the surgeon will assess the patient todetermine whether the material is likely to be hard or soft/gelatinous.This assessment might include an evaluation of one or more factors suchas the response of the tip of the guidewire or separator when it isbrought in contact with the thromboembolism, the location of thethromboembolic material, patient symptoms, and/or the manner in whichthe stroke caused by the thromboembolism is manifesting itself.

As discussed in connection with the first exemplary method, the guideand occlusion catheter 12 is introduced into the patient's vasculature,and the occlusion balloon 28 is inflated to arrest the flow of bloodwithin the vessel (see, for example, FIGS. 14-16).

The delivery and aspiration catheter 14 is passed through the guide andocclusion catheter 12 and positioned with its distal end at a locationproximal to the thromboembolism 100. If the surgeon elects to use theseparator 16 a prior to using the receiver 146, or if the assessmentresults in a determination that the thromboembolic material is likely tobe somewhat soft or gelatinous, the aspiration pump 18 is activated toestablish negative pressure within the delivery and aspiration catheter14, and thus to exert negative pressure exerted upon the thromboembolism100 to draw embolic material into the catheter 14.

The separator 16 a is deployed from the distal end of the delivery andaspiration catheter 14 and moved into contact with the thromboembolicmaterial 100 as shown in FIG. 24. The separator may be advanced andretracted multiple times if desired. When advanced and retracted asshown, the separator can facilitate aspiration of the thromboembolicmaterial into the catheter 14 in one of a variety of ways. First,movement of the separator into contact with the thromboembolism canloosen, separate, or soften pieces of thromboembolic material, such thatpieces of the thromboembolism can be aspirated into the catheter.Second, advancing and retracting the separator 16 a serves to remove anyclogs or flow restrictions within the lumen 36 of the delivery andaspiration catheter 14 that might be caused by the passage ofthromboembolic material through the lumen 36. Additionally, duringretraction of the disrupter 16 a, its proximal surface 35 may push orplunge loosened material towards and/or into the distal end of thecatheter 14 for subsequent aspiration out of the body.

If use of the disrupter 16 a as just described reveals that the vesselincludes a hard mass of thromboembolic material incapable of aspirationwithout further intervention, the disrupter 16 a is preferably withdrawnfrom the catheter 14 and a thromboembolic receiver 146 is passed throughthe delivery and aspiration catheter 14 and deployed within the bloodvessel. If the system is provided with multiple sizes of receivers, thesurgeon will select a receiver having an appropriate size for the bloodvessel being treated.

Referring to FIGS. 25-28, once the receiver 146 is deployed, it expandsinto contact with the surrounding walls of the vessel. As the receiver146 is advanced towards the body thromboembolic material 200, the wallsof the receiver 146 slip around the body 200 to engage and/or envelop(partially or fully) the thromboembolism. The engaging elements 170engage the thromboembolism 200, thereby retaining it within thereceiver. If desired, the delivery and aspiration catheter 14 may beadvanced slightly in a distal direction as indicated by arrows in FIG.27, so as to “cinch” the strut members 162 towards one another, thuscausing the receiver 146 to collapse slightly in a radially inwarddirection. Additionally, the aspiration pump 18 (FIG. 1) may beactivated to facilitate retention of the thromboembolism 200 within thereceiver. The delivery and aspiration catheter 14, the receiver 146 andthe thromboembolism 100 are withdrawn into the guide and occlusioncatheter 12 and are withdrawn from the body. If additionalthromboembolic material should remain in the blood vessel, a newdelivery and aspiration catheter 14 may be passed into the blood vessel,and a new receiver may be deployed through the catheter 14 forretrieving the additional body of thromboembolic material.

Naturally, the surgeon may elect to initially deploy the receiver ratherthan the separator, such as if the initial assessment results in adetermination that the thromboembolic material is likely to be hard. Themethod is then carried out utilizing the receiver 146 as described inthe preceding paragraph. If it is later determined that residualthromboembolic material (e.g. soft or gelatinous material) is present inthe vessel, the receiver 146 is preferably removed from the body, andthe separator 16 a is passed through the delivery and aspirationcatheter 14. The aspiration pump 18 is activated and the separator 16 ais manipulated to facilitate aspiration of the soft material in themanner described above.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the invention is to cover allmodifications, equivalents, and alternative falling within the spiritand scope of the invention.

1. An apparatus for withdrawing thromboembolic material from a bloodvessel, the apparatus comprising: an elongate member; and a receiver ona distal portion of the elongate member, the receiver formed of aplurality of structural members arranged to form a sleeve having acentral lumen, a first plurality of the structural members comprisinglongitudinally extending struts, a second plurality of the structuralmembers comprising v-shaped engaging elements, and a third set ofstructural members comprising a plurality of axially spaced-apartcircumferential rings attached to the longitudinal struts, each of saidv-shaped engaging elements being disposed between adjacent ones of thelongitudinal struts and including a first leg extending into the centrallumen from a first longitudinal strut and a second leg extending intothe central lumen from a second, adjacent longitudinal strut, said firstand second legs attached to one another within the central lumen todefine a plurality of longitudinally oriented apexes extending into thecentral lumen, wherein at least a distal row and a proximal row of thev-shaped engaging elements are disposed between a distal circumferentialring and a proximal circumferential ring and each apex is unattached toany other structure within the central lumen.
 2. The apparatus of claim1, wherein the receiver is radially expandable from a compressedposition in which the receiver is sized for passage into a blood vessel,to an expanded position in which the receiver is sized to contact aninner surface of the blood vessel when at body temperature.
 3. Theapparatus of claim 2, wherein, in the expanded position, the receiver isslidable over a body of thromboembolic material within the blood vesselto receive the body into the central lumen, and wherein the engagingelements are oriented to engage the body within the lumen.
 4. Theapparatus of claim 2, wherein, in the expanded position, the receiverhas a maximum expanded diameter in the range of approximately 2-6 mm. 5.The apparatus of claim 2, wherein, in the expanded position, thereceiver has a maximum expanded diameter in the range of approximately6-9 mm.
 6. The apparatus of claim 2, further including a catheter havinga catheter lumen, the receiver insertable into the catheter lumen whenin the compressed position, the receiver configured such thatadvancement of the receiver out of the catheter causes the receiver toself-expand to its expanded position.
 7. The apparatus of claim 6,wherein the receiver is configured such that withdrawal of the receiverinto the catheter causes the receiver to collapse to the compressedposition.
 8. The apparatus of claim 1, wherein the distalcircumferential ring is positioned at a distal end of the receiver. 9.The apparatus of claim 1, wherein the proximal circumferential ring ispositioned at a proximal end of the receiver.
 10. The apparatus of claim1, wherein a plurality of the longitudinal struts extend between thecircumferential rings.
 11. The apparatus of claim 1, wherein eachlongitudinal strut includes at least one spring region.
 12. Theapparatus of claim 1, wherein the plurality of circumferential ringsincludes an intermediate ring, and wherein the distal row of v-shapedelements is positioned between the distal ring and the intermediatering, and the proximal row of v-shaped elements is positioned betweenthe intermediate ring and the proximal ring.
 13. The apparatus of claim1, further including: an elongate sheath having a sheath lumenproportioned to receive the elongate member; and an occlusion balloon onthe sheath, the balloon inflatable to occlude flow of blood within ablood vessel.
 14. The apparatus of claim 1, wherein the receiver isexpandable from a first position to a second, radially expandedposition, and wherein the engaging elements are foldable during movementof the receiver from the second position to the first position.
 15. Theapparatus of claim 1, further comprising a plurality of v-shapedelements which include apex regions peripheral to the central lumen. 16.An apparatus for withdrawing thromboembolic material from a bloodvessel, the apparatus comprising: an elongate member; and a receiver ona distal portion of the elongate member, the receiver formed of aplurality of structural members arranged to form a sleeve having acentral lumen, the structural members including longitudinal strutmembers, v-shaped engaging elements and a plurality of axiallyspaced-apart circumferential rings attached to the longitudinal struts,each v-shaped engaging element being disposed between adjacent ones ofthe longitudinal struts and including a first leg extending from a firstlongitudinal strut member and a second leg extending from a secondlongitudinal strut member from a fixed position thereon, said secondlongitudinal strut member adjacent to the first longitudinal strutmember, the first leg forming an apex with the second leg, the apexextending into the central lumen, wherein at least a distal row and aproximal row of the v-shaped engaging elements are disposed between adistal circumferential ring and a proximal circumferential ring andwherein the first and second legs extend from a position that islongitudinally fixed relative to the first and second strut members andeach apex is unattached to any other structure within the central lumen.17. The apparatus according to claim 16, wherein the longitudinal strutmembers have distal ends and the distal circumferential ring extendsbetween the distal ends of the longitudinal strut members, the distalcircumferential ring formed of a plurality of strut members extendinggenerally perpendicular to the longitudinal strut members.
 18. Theapparatus of claim 17, wherein the receiver has a distal end, whereinthe longitudinal strut members extend to the distal end of the receiver,and the distal circumferential ring is on the distal end of thereceiver.
 19. The apparatus of claim 18, wherein the receiver has aproximal end, and wherein the longitudinal strut members extend betweenthe distal and proximal ends of the receiver.
 20. The apparatus of claim17, wherein the elongate member is a tubular member, wherein thelongitudinal strut members include proximal ends coupled to the tubularmember.
 21. The apparatus of claim 17 wherein: the receiver is radiallyexpandable from a compressed position to an expanded position and theplurality of circumferential rings include a plurality of bend regions,the circumferential rings bendable at the bend regions during movementof the receiver from the expanded position to the compressed position.22. The apparatus of claim 16, wherein the receiver is expandable from afirst position to a second, radially expanded position, and wherein theengaging elements are foldable during movement of the receiver from thesecond position to the first position.
 23. The apparatus of claim 16,wherein the distal circumferential ring defines an opening to thecentral lumen.